| Transportation Operations and Policy: Survey Course | Courses Index | | |
Page 5
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pages. Chapter: 3: Modal and Network Characteristics  |
Infrastructure/TerminalsInfrastructure includes both the roadway and terminals. Roadways are related to vehicle and motive power design through vehicle loads and by the grades and curvatures that place constraints on vehicle size, speed, and tractive effort. Roadways are also related to operational control through route capacity, guidance, and vehicular separation. The land area devoted to the route and facilities of railroads, highways, canals, pipelines, and conveyors is the right of way or 'reserve'. Natural waterways have their own basins and riverbeds. Pipelines are laid within the earth itself, preferably below the frost line. Airways are related to the terrain only by visual or radio-range route makers and at airport runways and taxiways. The characteristics of roadways are covered elsewhere and this chapter deals with terminal facilities. The characteristics of road network, railway network and waterways are given in figure 2.1. The Road Network The road network covers the whole country including all the classes of roads as shown in figures 2.1 and 2.2. The length of the various classes and number of bridges are given in table 2.1.
Table 2.1 Length of various classified roads. Source: National Roads Authority Road Network Value – May 2002
The railway network covers the Southern and Central Regions only as shown by the map shown in figure 2.1. The characteristics of the railway track are highlighted below. Rails The mainline essentially consists of BS 80 A class rail (40kg/m equivalent) with few sections in BS 60A class rail (30 kg/m equivalent) manufactured to British Standards. Rails are generally in fair condition having been installed in the late 1970s and early 1980s. Sleepers These are mostly of mono block prestressed concrete type with shoulders to fit Pandrol clip type of rail fasteners. There are few sections with steel sleepers on the mainline but the intention is to standardize on BS 80A rails on concrete sleepers. Wooden sleepers are generally used under turnouts, on open girders bridges and some light traffic sidings. Pandrol clips and clip-and-bolt type of fasteners are used on steel sleepers while coach screws and spikes are used on wooden sleepers. Ballast Crushed stone ballast is used on the mainline with a minimum density of 1000 cubic metres per kilometer. Gravel is used as ballast in sidings and other secondary tracks. Track Geometry The steepest gradient in hilly sections is 1 in 40 compensated for curvature but most sections have gradients of 1 in 80 and 1 in 100 or flatter. The sharpest curves are 110m radius and this is restricted to the hilly sections and at station yards. Most curves are greater than 200m radius. The maximum cant or super elevation is 75 mm. The gauge is 1067mm with an allowance for gauge widening on curves of 19mm maximum. The structure and loading gauge limits used are similar to the ones used in east and southern African Railways. Bridges and Culverts These are mostly constructed with steel superstructures-open girder spans supported on reinforced concrete or masonry piers and abutments on pad or pile foundations. Most bridges have spans between 6m and 17m except those on the Shire river which are about 30m. There are also a few bridges that have steel box girders and some with reinforced concrete trough girder spans. Most of the smaller waterway crossings are made with either reinforced concrete or corrugated steel pipe culverts. Waterways The route of the water carrier is about 700 kms from Monkey Bay in Mangochi to Kambwe in Karonga. There are twenty stations for the water carrier. The characteristics of the waterways are shown in figure 2.1. Airways The Government has built airports in Blantyre, Lilongwe and Mzuzu with aerodromes in all districts and Club Makokola.
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